JPS6262054A - Feed screw device - Google Patents

Abstract

PURPOSE:To accomplish silent operation by rotatably supporting a ring on a block, which faces a lead angles of a thread groove of a rotary shaft and is inscribed in the thread groove, whereby the rotary drive and the rectilinear drive can be converted to each other to be transmitted by rolling contact of the ring. CONSTITUTION:A rotary shaft 1 has two spiral thread grooves 1a formed on the outer periphery thereof. Two rings 2, the inner periphery of which are formed semi-circular in section are respectively rotatably supported on a block 3 formed like a substantially trigonal prism. The respective rings 2 are rotatably supported by ball bearings comprising steel balls 4 disposed on the outer periphery thereof and outer races 5, 6, and the ball bearings are fixed to the block 3 by bolts 7. The block 3 has a through hole 3d permitting the rotary shaft 1 to pierce therethrough formed between support surfaces 3a, 3b supporting the rings 2. Support angles alpha of the support surfaces 3a, 3b are set substantially equal to a lead angle of the thread groove 1a.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a feed screw device, and is used, for example, as a device for converting rotational motion of a rotating shaft into linear motion of a block, and is used in various robots, machine tools, and industrial applications. Used in machinery, etc.

[Conventional technology]

Conventionally, as a feed screw device, a method of transmitting power by sliding a screw shaft formed with a triangular screw, trapezoid screw, square screw, etc. and a screw surface of a NAND, and a ball screw device or a spiral screw device as shown in Fig. 8 have been proposed. - There is a method of transmitting power by interposing a large number of steel balls 52 between the screw shaft 50 and the thread groove of the nut 51, as in the case of ball splines (for example, technical magazine, Nikkei Mechanical, December 17, 1984). ``Devised a new type of ball-wound integer winding and non-slip structure based on life tests.''

However, the former has the problem of low mechanical efficiency and the inability to rotate the screw shaft or nut at high speed due to power transmission by sliding, and the latter has steel balls built in in a notation format, so it is difficult to use steel balls. There were problems such as noise, friction, and wear caused by the sound of collisions between steel balls, and, especially in pole screws, steel balls falling off during handling, and high-speed feeding being impossible due to the limit of the lead angle. .

[Problem that the invention seeks to solve]

The present invention has been made in view of the above problems, and includes:
The purpose is to provide a feed screw device that achieves high mechanical efficiency, is quiet without generating noise, and is capable of high-speed feeding due to a large lead angle.

[Means for solving problems]

Therefore, the configuration includes a rotating shaft with a spiral thread groove formed on the outer periphery, and a lead angle of the thread groove of the rotating shaft,
and a ring inscribed in the thread groove of the rotating shaft, and supporting the ring rotatably and rotatably supported with respect to the rotating shaft or supported so as to be linearly movable in the axial direction of the rotating shaft. It is characterized by comprising a block.

[For production]

According to the above configuration, for example, when the rotating shaft is rotationally driven, the ring rotatably supported by the block rotates along the thread groove of the rotating shaft, so that the block is aligned in the axial direction of the rotating shaft. Movement: so-called feed movement. Further, when the block is rotationally driven, the rotation shaft is moved in the axial direction by the operation of the ring and the thread groove of the rotation shaft.

〔Example〕

Next, one embodiment of the present invention will be described based on FIGS. 1 and 2. FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a partial sectional view taken along a plane parallel to the rotational axis of the ring, including line A--A in FIG. 1.

Reference numeral 1 in the figure is a rotating shaft having two spiral thread grooves 1a formed on its outer periphery, and the thread grooves 1a are semicircular grooves in a cross section perpendicular to the thread grooves 1a.

Two rings 2, each having a convex semicircular inner periphery cross section so as to engage with the thread groove 1a, are supported by the block 3 so as to be inscribed in each groove of the two threads 1a. ing. As shown in FIG. 2, the ring 2 is rotatably supported by a ball bearing consisting of steel balls 4 and an outer race 5.6 provided on its outer periphery, and the outer race 5.6 is fixed to the block 3 by bolts 7. has been done. The code 8 is
Two rings 2 and the screw on rotating shaft 1? In order to properly adjust the dimensional relationship with J11a, block 3 and outer race 6
It is a ring-shaped spacer interposed between the

The block 3 that rotatably supports the ring 2 has a substantially triangular prism shape, and has support surfaces 3a and 3b that support the ring 2.
A through hole 3d parallel to the bottom surface 3C is formed between them so that the rotating shaft 1 is disposed therein. Further, the support angle α formed by the plane perpendicular to the axis of the rotating shaft 1 and the supporting surfaces 3a and 3b is the lead angle of the rotating shaft 1, that is, the helical expansion of the helical thread groove 1a on the cylindrical surface of the rotating shaft 1. The ring 2 is set at an angle approximately equal to the angle formed by the spiral of the thread groove 1a with respect to a plane perpendicular to the axial direction of the rotating shaft 1, which is obtained when the ring 2 is aligned with the thread groove of the rotating shaft 1. 1a
The block 3 is supported by support surfaces 3a and 3b of the block 3 so as to be able to rotate smoothly along the block 3.

Note that the above lead angle was considered based on the effective diameter of the rotating shaft 1, but the lead angle differs somewhat when considered based on the outer diameter of the rotating shaft 1 or the inner diameter of the valley portion of the thread groove 1a. Preferably, the support angle α is approximately equal to the lead angle in terms of the effective diameter, or is between the maximum and minimum values of these lead angles.

As shown in Fig. 1, one of the two rings 2 is inscribed and engaged with the thread groove 1a in the upper part of the figure, and the other ring is inscribed and engaged with the thread groove 1a in the lower part of the figure. By being attached to the support surfaces 3a, 3b of the block 3 in this manner, the bending stress acting on the rotating shaft 1 from the ring 2 is canceled out as much as possible. However, the rotation axis 1
If there is sufficient bending strength in
It goes without saying that it is also possible to inscribe and engage with. However, at this time, the support surface 3b of the block 3 is
parallel to the support surface 3a shown in the figure, or the support surface 3a is the first
parallel to the support surface 3b shown in the figure, and the block 3
becomes a quadrangular prism having a parallelogram base with the supporting surfaces 3 a + 3 b as two sides.

Next, the operation will be explained.

In the above configuration, one end of the rotating shaft 1 is connected to a drive motor etc. to enable rotational driving, and the block 3 is moved along the linear guide provided along the axial direction of the rotating shaft 1 (
When the rotating shaft 1 is driven to rotate, the ring 2, which is rotatably supported by the block 3, moves along the thread groove 1a of the rotating shaft 1. Due to the rotating action, the block 3 is driven linearly along the guide without rotation, ie it is driven forward.

Further, when the rotating shaft 1 is restricted from rotating and is supported slidably in the axial direction, and the block 3 is rotationally driven, the ring 2 and the thread groove of the rotating shaft 1
By the operation of a, the rotary shaft 1 is sent in its axial direction and linearly driven.

In addition, by the operation of the thread groove 1a of the rotary shaft 1 and the ring 2 rotatably supported by the block 3, the linear drive of the rotary shaft 1 becomes the rotational drive of the block 3, and the linear drive of the block 3 becomes the rotational drive of the block 3, contrary to the above. Needless to say, it is also possible to transmit and convert the rotational drive of the rotating shaft 1.

The spacer 8 is a part for adjusting the dimensional difference due to machining of the components of the feed screw device, and when the ring 2 is inscribed in the thread groove 1a of the rotating shaft l, depending on the purpose of use, the spacer 8 Appropriate preload or clearance is applied between them, and at this time, the preload and clearance can be easily set by simply changing the length of the spacer 8.

Next, an example in which the above-mentioned feed screw device is applied to a right-angle device robot will be explained based on FIGS. 3 to 5.

3 is a perspective view of the Cartesian coordinate robot, FIG. 4 is a cross-sectional view taken along the line D--D in FIG. 3, and FIG. 5 is a cross-sectional view taken along the line E--E in FIG. 3.

This Cartesian coordinate robot includes an X slide frame 16 that slides along the X axis, a tool 21, and a tool drive motor 2.
2 and a Y slide frame 17 that slides along the Y axis. This slide frame 16.1
7 are each linearly driven by the above-mentioned feed screw device.

A slide frame 16 is provided on the upper surface of the guide frame 13.
A sliding surface is formed that slides along the longitudinal direction of the frame 13, and bearings 15 are provided at both ends of the frame 13, as shown in FIG. Support freely. The above-mentioned block 3 that fits into the rotating shaft 1 is provided at the lower part of the X slide frame 16. As described above, this block 3 has a ring 2 inscribed in the thread groove of the rotating shaft 1, and is fixed to the X slide frame 16. Therefore, guide frame I
When the X-axis drive motor 11 fixed to the X-axis drive motor 11 rotates, the rotary shaft 1 connected to the motor 11 through the coupling 12 rotates, and the aforementioned operation of the rotary shaft 1 and block 3 causes the block 3 and the X slide frame 16 to rotate. is linearly driven along the guide frame 13 in the X-axis direction.

Guide frame 1 fixed to X slide frame 16
8. The guide bar 19 supports the Y slide frame 17 slidably in the Y-axis direction by a bearing attached to the Y slide frame 17.

Further, a bearing 15 that rotatably supports the rotating shaft 1 is provided at one end of the X slide frame 16 and the guide frame 18. Further, the block 3 is fixed within the Y slide frame 17 in the same manner as the block 3 is fixed to the X slide frame 16. Therefore, frame 1
When the X-axis drive motor 11 fixed to the
The block 3 and the Y slide frame 18 move into the Y position by the operation of the rotating shaft 1 and the block 3 as described above.
It is linearly driven along an axial guide bar 19.

If the lead angle of the rotating shaft 1 on which the threaded groove is formed is increased, the amount of linear movement of the block 3 per revolution of the motor 11 will be increased, and this can be done without increasing the outer diameter of the rotating shaft 1. It becomes possible to feed and drive the X and Y slide frames 16 and 17 at high speed without increasing the rotational speed of the motor 11. In the above embodiment, the lead angle of the thread groove 1a could be set to 45 degrees or more.

Next, an example in which the feed screw device according to the present invention is applied to a bolt tightening rotation drive device will be explained based on FIGS. 6 and 7. Figure 6 is a perspective view of the bolt tightening rotary drive device;
The figure shows its longitudinal cross-section.

A driver bit 31 is attached to one end of the rotating shaft 1 formed with a thread groove 1a via an output shaft portion 1b, and is rotatably supported by a bearing 34 attached to a cylinder 32 and a cylinder cover 33. There is. Inside the cylinder 32, a block 3 having a ring 2 inscribed in the thread groove 1a of the rotating shaft 1 and a block 47 fixed to this block 73 with a bolt 46 are slidably housed as a piston. The block 47 partitions the inside of the cylinder 32 into two pressure chambers 42 and 43. The pressure chambers 42, 43 each have a hydraulic boat 44.43 formed in the cylinder cover 33. Pressure oil is supplied via a hydraulic boat 45 formed in the cylinder 32 .

The outer peripheral surfaces of this block 3 and block 47 are
It has a cylindrical shape so that it can slide within the cylinder 32.

Further, a guide pin 35 whose one end is press-fitted into the cylinder cover 33 is slidably passed through the block 3 and the block 47, and the rotation of the block 3 and the block 47 is regulated by the guide pin 35.

Note that the pressure chambers 42 and 43 are connected to the block 3 and the block 47.
They are separated by a sealing O-ring 36 on the side and an O-ring 37 provided around the outer periphery of the guide pin 35.

Inside the annular seal member 41, there is a threaded groove 1a of the rotating shaft 1.
The seal protrusions 41a are formed in a shape corresponding to the thread groove 1a and in a number corresponding to the thread number of the thread groove 1a.
The pressure chambers 42 and 43 are sealed to prevent communication through them. In addition, numerals 38 and 39 are O-rings for sealing, and 40
is a plate member fixed integrally with the cylinder cover 33.

This embodiment shows a case in which the ring 2, the steel balls 4 supporting it, and the outer race 5.6 are one set. In this case, it goes without saying that the rotating shaft 1 may have only one thread groove 1a.

In the bolt tightening rotation drive device described above, the hydraulic boat 4
When the pressure in the pressure chamber 43 to which pressure oil is supplied from the block 5 increases, the block 5, which is a piston, slides within the cylinder 32 in the direction of the arrow shown in FIG. 7 in response to hydraulic pressure. This sliding is
The operation of the ring 2 of the block 3 and the screw lla converts the rotating shaft 1, the output portion 1b, and the driver bit 31 into rotational drive in the direction of the arrow, thereby rotationally tightening a bolt (not shown). Note that when the rotation is reversed in the direction of the arrow, pressure oil is supplied from the hydraulic boat 45.

It goes without saying that if the lead angle of the threaded groove 1a is increased, the rotational torque obtained from the output portion 1b will be increased even if the outer diameter of the block 5 and the oil pressure are the same.

Therefore, when the feed screw device of the present invention is applied, this lead angle can be increased and the machine efficiency is improved, so even if the conventional piston with the same oil pressure and the same outer diameter is used, it can generate large torque. Moreover, stable rotational driving force can be obtained.

In the above embodiment, the thread groove 1a formed on the outer periphery of the rotating shaft 1 and the inner periphery of the ring 2 were semicircular, but this shape may be a V-shape or a combination of part of a circular arc. The ring 2 may have a similar shape, or may have another shape in which the thread groove 1a and the ring 2 fit together. Further, in the above embodiment, two thread grooves 1a
It is constructed by fitting two rings 2 or one thread groove 1a and one ring, but the thread ala
It goes without saying that the same effect can be obtained even if the number of threads and the number of rings 2 are other than those mentioned above.

〔Effect of the invention〕

As described above, since the feed screw device according to the present invention has a structure in which a thread groove formed on the outer periphery of the rotating shaft and a ring facing the thread groove are inscribed, it has the following effects.

First, the feed screw device of the present invention transfers and converts rotational drive into linear drive, or vice versa, by rolling contact of a ring rotatably supported by a block, and vice versa. Problems with ball screws such as collision between steel balls 52 and return tube portion 5 shown in FIG.
Noise generated by the irregular movement of the steel balls 52 at 3 is eliminated, resulting in very quiet operation and high mechanical efficiency.

Secondly, the conventional ball screw has a screw shaft 50 and a nut 51.
Since the screw shaft 50 is configured to engage a threaded groove inside the nut 51 with a steel ball 52 interposed between them, the female thread 51a formed inside the nut 51 has a constant lead angle due to processing constraints. Whereas it was not possible to increase the lead angle by more than 18 degrees (approximately 18 degrees), the present invention has a structure in which a ring is inscribed in the thread groove of the rotating shaft, so the lead angle of the thread groove can be increased. Therefore, when the feed screw device of the present invention is adopted in a machine tool or the like and the lead angle is increased, the shaft outer diameter is the same as that of the conventional high-lead ball screw for high-speed feed (ball screws whose screw shaft diameter and lead are equal). When compared at the same rotational speed, linear drive that is more than twice as fast, ie, high-speed feed drive, is possible.

Thirdly, the feed screw device of the present invention has an extremely simple structure in which the ring is rotatably supported within the block, so it is inexpensive and has good durability. There are many excellent effects such as high feed accuracy as there is no slippage or wear during the process.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the feed screw device of the present invention, and is shown with a block seen through. FIG. 2 is a partial sectional view taken along the plane parallel to the rotational axis of the ring 2, including line A-A in FIG. 1, and FIG. 3 is a perspective view showing an example of a Cartesian coordinate robot to which the feed screw device of the present invention is applied. Figure 4 is a partial sectional view taken along line D-D in Figure 3, and Figure 5 is a partial sectional view taken along line EE' in Figure 3. 6 is a perspective view of a bolt tightening rotary drive device to which the feed screw device of the present invention is applied, FIG. 7 is a vertical sectional view of the device shown in FIG. 6, and FIG. 8 is a conventional one. It is a sectional view showing a ball screw.

Claims (2)

[Claims] (1) A rotating shaft with a spiral thread groove formed on its outer periphery, a ring that faces the lead angle of the thread groove of the rotating shaft and is inscribed in the thread groove of the rotating shaft, and a ring that is rotatable. A feed screw device comprising: a block that supports the rotary shaft and is rotatably supported with respect to the rotary shaft, or supported so as to be linearly movable in the axial direction of the rotary shaft. (2) The support surface of the block that rotatably supports the ring is provided to have a support angle approximately equal to the lead angle of the thread groove of the rotation shaft with respect to a plane perpendicular to the rotation shaft. A feed screw device according to claim 1.